Light beams or optical signals are frequently used to transmit digital data between electronic devices, both over long distances and between adjacent circuit boards, between components on a single circuit board, and may even be used between devices on the same chip. An optical signal may also be used for other purposes including position or motion sensing, measurement, reading encoded data, etc.
Consequently, optical technology plays a significant role in modern electronics, and many electronic devices employ optical components. Examples of such optical components include, but are not limited to, optical or light sources such as light emitting diodes and lasers, waveguides, fiber optics, lenses and other optics, photo-detectors and other optical sensors, optically-sensitive semiconductors, and others.
Often, optical resonators are used to selectively filter, switch, or modulate light beams that are used, for example, to transmit data between electronic components. Ring resonators are a type of optical resonator that comprise an optical waveguide in a closed loop. The ring resonator is coupled to a tangential waveguide. When light of an appropriate wavelength is introduced into the loop by the tangential waveguide, the light beam can be manipulated in intensity or amplitude over multiple circuits around the ring resonator. However, optical losses due to scattering and absorption within the ring resonator can reduce the overall efficiency of the ring resonator, resulting in less than optimal performance. Scattering can be caused by rough surfaces at boundaries between materials with different indices of refraction. Absorption can be caused by interaction of the optical energy with absorptive impurities or materials contained in the ring resonator structure.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.